Many years ago I purchased an excellent coffee grinder. But there's one feature on this grinder that I've never really experimented with... I can control the speed of grinding using a dial on the right hand side of the grinder with the speed maxing out at 800 revolutions per minute. I've been grinding at 600 rpm until this morning.
Regular readers of my newsletter will understand that I love a bit of basic physics mixed with my morning espresso. In this instance, the basic physics relates to the concept of surface area to volume ratio. The short version is that given the same geometric proportions, a smaller object will have a higher surface area to volume ratio than a larger object. It's the reason why human babies are more susceptible to the elements than adults (greater surface area means that little humans gain or lose heat to the outside environment quicker than larger humans). Similarly your fingers and toes tend to be more affected by the cold than your torso (let's forget the confounding topic of clothing for a second).
In the context of coffee grinding, the received wisdom is that faster grinding produces a different distribution of coffee particle sizes. Faster grinding apparently produces more fines (small grind particles) and I believe that crazy coffee scientists have demonstrated this using electron microscopy (insane I know!).
The end result of grinding with higher rpm this morning was a very satisfying cup. In particular I noticed that my espresso shot had noticeably more body (something I really find very satisfying). I'll keep experimenting and let you know what I find.